This is a follow-up study looking at the and long-term results of two methods of preparing the thigh bone to receive an implant during hip replacement surgery. For one group of patients in the original study, the surgeon used a cutting tool called a broach and a special hammer on patients who had standard hip replacement operations. For the other patients, the surgeon used a surgical robot which was equipped with a cutting tool, like a drill, to prepare the thigh bone. The purpose of this study is to collect additional information confirming that the surgical robot is safe and effective when used as recommended. Only patients who were enrolled in the original clinical trials are eligible for this study.

A. Description This study is a follow-up study looking at mid- and long-term outcomes for participants in the IDE G920035 and IDE G000071 Clinical Trials. The IDE G920035 was a randomized, controlled trial with a 1:1 ROBODOC:control randomization. The IDE G000071 was a randomized, controlled trial with a 3:1 ROBODOC:control randomization.

B. Selection Criteria Only subjects who were originally enrolled in the IDE G920035 and IDE G000071 Clinical Trials are eligible to participate in this study. Subjects selected for this study will have completed a minimum of the 3 month follow-up requirements of the IDE G920035 and IDE G000071 Clinical Trials. Enrolled subjects must be willing to give a relevant medical history, undergo a focused physical examination of their operative hip(s), have an AP and lateral x-ray taken of their operative hip(s) and complete the Harris Hip Score, SF-12, UCLA Activity Score, VAS pain self-assessment, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires.

The study subject may be reimbursed for reasonable travel expenses associated with their participation in the study. All requests for reimbursement must be pre-approved by Curexo Technology Corporation.

C. Data Collection Subjects participating in this study will be asked to visit the study site to undergo a physical examination of their operative hip(s). During this visit, they will be asked to give a relevant medical history, have AP and lateral radiographs taken of their operative hip(s), and complete the Harris Hip Score, SF-12, UCLA Activity Score, VAS pain self-assessment, and WOMAC questionnaires.

If the subject has obtained AP and lateral radiographs within the last year, these can be used instead of requiring them to obtain new radiographs specifically for this study.

If the subject is unable or unwilling to come in for the examination, they will be asked to fill out the Harris Hip Score, SF-12, UCLA Activity Score, VAS pain self-assessment, and WOMAC questionnaires via mail or over the phone with the Study Nurse/Coordinator. Additionally, they will be asked to obtain current AP and lateral radiographs taken of their operative hip(s) with their current orthopaedic surgeon to be transferred to the study site.

D. Blinding An independent radiologist or orthopaedic surgeon, experienced in reading hip x-rays, who is blinded to the original randomly assigned study group, will read the follow-up x-rays taken on subjects enrolled in this study.

E. Randomization There will be no further randomization of subjects in this study. Prior subject records will determine the original study group (ROBODOC or manual control) to which the subject was randomly assigned in IDE G920035 or IDE G000071.

F. Baseline Measurements No baseline measurements will be collected for this follow-up study. G. Power and Sample Size The sample size will be determined by the number of qualifying subjects from the IDE G920035 and IDE G000071 Clinical Trials who can be located and who agree to participate in this follow-up study. We anticipate approximately 20 patients from IDE G920035 and 30 patients from IDE G000071 to agree to study participation. This sample size will provide 82% power (α = 0.05, 2-tailed) to detect a 20% (5 versus 2.5, pooled SD = 3.0) difference between the ROBODOC and control groups on the VAS at the last available follow-up.

Inclusion Criteria:

• Subjects included in this study will have completed the follow-up requirements of the IDE G920035 or the IDE G000071 Clinical Trial;
• Subjects must be willing to give a relevant medical history, undergo a focused physical examination of their operative hip(s) and have an AP and lateral x-ray taken of their operative hip(s);
• Subjects must be willing to complete the Harris Hip Score, SF-12, WOMAC, UCLA Activity Score, and VAS pain self-assessment questionnaires; and
• Subjects must be willing to sign an informed consent document.

Exclusion Criteria:

• There are no exclusion criteria.

Subjects included in this study will have been enrolled in either the IDE G920035 or the IDE G000071 Clinical Trial and will have completed the follow-up requirements to those trials.

Patients enrolled in IDE G920035 trial or IDE G000071 trial and underwent total hip arthroplasty using either the ROBODOC Surgical Assistant System or a manual technique.

2 years, 2 months